Scanning sequence for an intra-oral imaging system

ABSTRACT

Provided are a system, method, and computer readable storage medium for generating an intra-oral scan of a dentition. A contiguous scan of an occlusal surface of at least a part of one arch of the dentition is generated. At least one additional surface is associated to the contiguous scan of the occlusal surface.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/209,648, filed Mar. 13, 2014, entitled SCANNING SEQUENCE FOR ANINTRA-ORAL IMAGING SYSTEM, which claims the benefit of U.S. ProvisionalPatent Application No. 61/784,535, filed Mar. 14, 2013, the entirecontents of both of which are incorporated herein by reference.

FIELD

The disclosure relates to a method, system, and computer readablestorage medium for a scanning sequence for an intra-oral imaging system.

BACKGROUND

An intra-oral imaging system is a diagnostic equipment that allows adental practitioner to see the inside of a patient's mouth and displaythe topographical characteristics of teeth on a display unit. Certainthree-dimensional (3D) intra-oral imagers may be comprised of anintra-oral camera with a light source. The 3D intra-oral imager may beinserted into the oral cavity of a patient by a dental practitioner.After insertion of the intra-oral imager into the oral cavity, thedental practitioner may capture images of visible parts of the teeth andthe gingivae. The 3D intra-oral imager may be fabricated in the form ofa slender rod that is referred to as a wand or a handpiece. The wand maybe approximately the size of a dental mirror with a handle that is usedin dentistry. The wand may have a built-in light source and a videocamera that may achieve an imaging magnification, ranging in scale from1/10 to 40 times or more. This allows the dental practitioner todiscover certain types of details and defects of the teeth and gums. Theimages captured by the intra-oral camera may be displayed on a displayunit. Additionally, three-dimensional surfaces generated from imagescaptured (i.e., scanned) by the intra-oral imaging system may bedisplayed on the display unit.

SUMMARY OF THE PREFERRED EMBODIMENTS

Provided are a system, method, and computer readable storage medium forgenerating an intra-oral scan of a dentition. A contiguous scan of anocclusal surface of at least a part of one arch of the dentition isgenerated. At least one additional surface is associated to thecontiguous scan of the occlusal surface.

In additional embodiments, the at least one additional surface comprisesa plurality of labial surfaces and a plurality of lingual surfaces.

In further embodiments, each scan of a labial or a lingual surfaceincludes a part of the occlusal surface, where the part of the occlusalsurface that is included in each scan of the labial or lingual surfaceis used to associate the labial or the lingual surface to the contiguousscan of the occlusal surface.

In yet further embodiments, each scan of the labial or the lingualsurface is performed by moving a wand in a predetermined pattern.

In certain embodiments, the occlusal surface is imaged prior to theplurality of labial and lingual surfaces to display in real-time athree-dimensional representation of the dentition.

In additional embodiments, the occlusal surface is imaged in a singlesegment, where the plurality of labial surfaces and the plurality oflingual surfaces are each imaged in a plurality of segments.

In yet additional embodiments, selected frames of the contiguous scan ofthe occlusal surface that have an overlap based on an analysis of data,are matched to generate an occlusal backbone.

In further embodiments, the overlap is based on noise characteristics ofthe data.

In additional embodiments, to perform a real-time display of athree-dimensional representation of the dentition, a coarse matching isperformed by matching features, prior to a three-dimensionalreconstruction based on a point cloud alignment.

In further embodiments, the occlusal backbone is a first occlusalbackbone, and other frames that are different from the selected framesare linked to the occlusal backbone to generate a second occlusalbackbone that is more accurate than the first occlusal backbone.

In certain embodiments, areas representing at least one of a tongue, acheek, and a lip, are removed from the second occlusal backbone togenerate a third occlusal backbone.

In further embodiments, the areas representing at least one of thetongue, the cheek, and the lip, are removed from the second occlusalbackbone, based on differences in surface normals, color, or rigidityproperties.

In additional embodiments, interferometric fringes are projected on theocclusal surface primarily along an anterior-posterior direction.

Provided also is an imaging system that comprises a projector thatprojects interferometric fringes on an occlusal surface of at least apart of one arch of a dentition primarily along an anterior-posteriordirection, and an imaging sensor that is used to view theinterferometric fringes.

In certain embodiments, the imaging system is configured to generate acontiguous scan of an occlusal surface, and associate at least oneadditional surface to the contiguous scan of the occlusal surface. Infurther embodiments, the at least one additional surface comprises aplurality of labial surfaces and a plurality of lingual surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 illustrates a block diagram of a computing and imagingenvironment that includes an intra-oral imaging system used to captureimages of a patient's teeth, in accordance with certain embodiments;

FIG. 2 illustrates a diagram that shows scanning of a dental arch, inaccordance with certain embodiments;

FIG. 3 illustrates a diagram that shows how lingual and labial scans areassociated with an occlusal backbone to generate a three-dimensionalsurface representation of a dental arch, in accordance with certainembodiments;

FIG. 4 illustrates a flowchart that shows how labial and lingual scansare attached to an occlusal backbone to display a three-dimensionalreconstruction of the dental arch, in accordance with certainembodiments;

FIG. 5 illustrates a diagram that shows interferometric fringesprojected on a dental arch, in accordance with certain embodiments;

FIG. 6 illustrates an exemplary sequence of occlusal frames, inaccordance with certain embodiments;

FIG. 7 illustrates a diagram that shows how selected frames with anexemplary 50% overlap are used to construct the occlusal backbone, inaccordance with certain embodiments;

FIG. 8 illustrates a diagram that shows how frames are matched toconstruct the occlusal backbone, in accordance with certain embodiments;

FIG. 9 illustrates a diagram that shows a representation of an occlusalscan with tongue, lips, and cheek, in accordance with certainembodiments;

FIG. 10 illustrates a diagram that shows how tongue, lips, and cheek areremoved from the occlusal backbone, in accordance with certainembodiments;

FIG. 11 illustrates a diagram that shows the movement of a wand in anexemplary pattern for labial or lingual scans, in accordance withcertain embodiments;

FIG. 12 illustrates a first phase of an exemplary surface reconstructionof a plurality of teeth by stitching first and second segments of alabial surface to an occlusal backbone, in accordance with certainembodiments;

FIG. 13 illustrates a second phase of an exemplary surfacereconstruction of a plurality of teeth by stitching a third segment alabial surface and a first segment of a lingual surface to an occlusalbackbone, in accordance with certain embodiments;

FIG. 14 illustrates a third phase of an exemplary surface reconstructionof a plurality of teeth by stitching second and a third segments of alingual surface to an occlusal backbone, in accordance with certainembodiments;

FIG. 15 illustrates a flowchart that shows how an accurate occlusalbackbone is generated by selecting frames that overlap, and by removingareas that represent the tongue, cheek, and lips, and how labial andlingual scans are attached to the occlusal backbone to display athree-dimensional reconstruction of the dental arch, in accordance withcertain embodiments;

FIG. 16 illustrates a flowchart that shows how labial and lingual scansare attached to an occlusal backbone to display a three-dimensionalreconstruction of the dental arch, in accordance with certainembodiments;

FIG. 17 illustrates a flowchart that shows how labial and lingual scansobtained by moving a wand in an exemplary pattern are associated with anocclusal backbone to display a three-dimensional reconstruction of thedental arch in accordance with certain embodiments;

FIG. 18 illustrates a flowchart that shows how at least one additionalsurface is associated with a contiguous scan of an occlusal surface, inaccordance with certain embodiments;

FIG. 19 illustrates a flowchart that shows how a plurality of labial andlingual surfaces are associated with a contiguous scan of an occlusalsurface, in accordance with certain embodiments; and

FIG. 20 illustrates a block diagram of a computational device that maycorrespond to the intra-oral imaging device shown in FIG. 1, inaccordance with certain embodiments.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings which form a part hereof and which illustrate severalembodiments. It is understood that other embodiments may be utilized andstructural and operational changes may be made.

Using an Intra-Oral Imaging System for Scanning a Dental Arch

A dental practitioner may insert a wand of the intra-oral imaging systeminto a patient's oral cavity to acquire images of the patient's teeth.In certain embodiments, the dental practitioner first acquires anocclusal scan of the patient's teeth in a single segment via anuninterrupted motion of the wand over the occlusal surface of the teeth.While performing the occlusal scan the wand may rest on the teeth andglide smoothly over the dental arch.

Subsequent to performing the occlusal scan, the dental practitioner mayuse the wand to acquire images of each of the lingual and labialsurfaces of the dental arch in a plurality of segments. The presence oflips, tongue, cheek, etc., makes it difficult to acquire images of thelingual and labial surface via an uninterrupted motion of the wand andtherefore each of the lingual and labial surfaces are imaged in multiplesegments.

In certain embodiments, the frames of the occlusal scan are merged intoan occlusal backbone to which the segments of the lingual and labialsurfaces are linked to generate a three-dimensional surface of thedental arch that is displayed in real-time on a display device.

The occlusal backbone is generated in multiple phases. In a first phase,in order to statistically limit the effect of random noise and otherimage characteristics, selected frames that overlap by about 50% (orsome other percentage) are stitched to form a rough occlusal backboneand then other frames are stitched to the rough occlusal backbone.Subsequently, areas representing tongue, cheek, and lips are removedfrom the occlusal backbone, and a restitching of frames is performed togenerate a more accurate occlusal backbone. The segments of lingual andlabial surfaces are then acquired by moving the wand in an exemplarypattern, such as, in the pattern of a hook. In each segment of thelingual and labial surface that is acquired, the movement of the wand inthe exemplary pattern ensures that part of the occlusal scan is alsoacquired. The part of the occlusal scan that is acquired is used tomatch the segments of the lingual and labial surfaces to the occlusalbackbone, and the three-dimensional surface of the dental arch isdisplayed on the display device.

The embodiments allow generation of a more accurate three-dimensionalsurface of the dental arch for real-time display, in comparison tosituations in which a contiguous occlusal scan is not used.

EXEMPLARY EMBODIMENTS

FIG. 1 illustrates a block diagram of a computing and imagingenvironment 100 that includes an intra-oral imaging system 102 used tocapture images of a patient's teeth 103, in accordance with certainembodiments.

The intra-oral imaging system 102 is comprised of a processor 104, adisplay unit 106, a wand 108, and a scanning and surface reconstructionapplication 110. In certain embodiments, the intra-oral imaging system102 may be coupled via a wired or wireless connection over a network toone or more computational devices (not shown), where the computationaldevices may include any suitable computational device such as a personalcomputer, a server computer, a mini computer, a mainframe computer, ablade computer, a tablet computer, a touch screen computing device, atelephony device, a cell phone, a mobile computational device, etc., andsome of the computational devices may provide web services or cloudcomputing services.

A dental practitioner may hold the wand 108 inside a patient's oralcavity. An optical source (e.g. the projector 105) included in the wand108 or coupled to the wand 108, may illuminate the oral cavity and theintra-oral imaging sensor 112 may be used to capture a plurality ofdigital images of structures in the oral cavity, such as the patient'steeth, gingivae, and/or, palate, and other structures, such as fillings,braces, etc. In certain embodiments the intra-oral imaging sensor 112may comprise an intra-oral camera.

The operation of the wand 108 may be controlled by the scanning andsurface reconstruction application 110 that may be implemented insoftware, hardware, firmware or any combination thereof. In certainembodiments, the display unit 106 of the intra-oral imaging system 104may include a touch screen display unit that displays scanning sequenceprompts 114 and three-dimensional surface reconstructions 116 of thepatient's dental arches. The scanning and surface reconstructionapplication 110 may process the images acquired by the intra-oralimaging sensor 112 and also display the images on the display unit 106and further transmit the images to one or more computational devicescoupled via a network to the intra-oral imaging system 102.

The patient's teeth 103 that are imaged via the intra-oral imagingsystem 102 may include a mandibular arch 118 and a maxillary arch 120.Each of the mandibular arch 118 and the maxillary arch 120 may includean occlusal surface 122, 124, a labial surface 126, 128 and a lingualsurface 130, 132.

Therefore, FIG. 1 illustrates certain embodiments in which an intra-oralimaging system 102 is used to acquire intra-oral images of the occlusal,labial, and lingual surfaces of the maxillary and mandibular arch of apatient. In the process of acquisition of images, the occlusal surfaceof a dental arch is acquired first via a single uninterrupted motion ofthe wand 108, followed by the labial and the lingual surfaces that areacquired in multiple segments. An occlusal backbone is generated fromthe image frames of the occlusal scan, and then the segments of thelabial and lingual scans are linked to the occlusal backbone to generatethe three-dimensional surface of the dental arch for real-time displayon the display unit 106.

FIG. 2 illustrates a diagram 200 that shows scanning of a dental arch,in accordance with certain embodiments. An exemplary occlusal scan 202that is generated by gliding the wand 108 over the occlusal surface of adental arch 118, 120 of the patient is shown. The viewing orientation ofthe intra-oral imaging sensor 112 for labial scan (shown via referencenumeral 204) and the viewing orientation of intra-oral imaging sensor112 for lingual scan (shown via reference numeral 206) are also shown.In the lingual scan, the side surfaces of the teeth that arepredominantly faced towards the tongue are imaged. In the labial scanthe side surfaces of the teeth that are predominantly faced towards thelips and cheek are imaged.

FIG. 3 illustrates a diagram 300 that shows how lingual and labial scansare associated with an occlusal backbone to generate a three-dimensionalsurface representation of a dental arch, in accordance with certainembodiments.

A representation of an occlusal backbone that is constructed from acontiguous occlusal scan is shown via reference numeral 302. Anexemplary segment of a labial scan 304 and an exemplary segment of alingual scan 306 are also shown. It may be noted that multiple segmentsof labial scan and lingual scan may be needed to cover the entire dentalarch.

In certain embodiments, the segments of the labial scan 304 and thesegments of the lingual scan 306 are attached (reference numerals 308,310) to the occlusal backbone 302 to generate a three-dimensionalsurface representation of the dental arch 312.

Therefore, FIG. 3 illustrates certain embodiments in which segments oflabial and lingual scans are attached to an occlusal backbone togenerate a three-dimensional surface representation of the dental archfor display on the display unit 106 of the infra-oral imaging system102.

FIG. 4 illustrates a flowchart 400 that shows how labial and lingualscans are attached to an occlusal backbone to display athree-dimensional reconstruction of the dental arch, in accordance withcertain embodiments. The operations shown in FIG. 4 may be performed viathe scanning and surface reconstruction application 110 that executesoperations on the processor 104 of the intra-oral imaging system 102. Incertain alternative embodiments, the operations shown in FIG. 4 may beperformed in one or more computational devices that are external to theintra-oral imaging system 102.

Control starts at block 402 in which the scanning and surfacereconstruction application 110 generates a contiguous scan of theocclusal surface of a dental arch of the patient. A contiguous scan is ascan that scans a part or the entirety of the dental arch in a singleuninterrupted motion of the wand. For example, in certain embodiments adental practitioner may place the wand on the occlusal surface of apatient's tooth on the last molar (i.e., third molar) at one end of thedental arch and glide the wand over the occlusal surface to the lastmolar (i.e., third molar) on the other end of the dental arch in about30 seconds and the corresponding scanning may be an example of acontiguous scan. It should be noted that the contiguous scan need notscan the entirety of the dental arch, but may scan a part of the dentalarch. Hundreds or thousands of image frames may be acquired during thescanning process, where each image frame may be an image of a part of atooth, an image of one tooth, or an image of a few teeth of the dentalarch. Successive frames may have overlapping regions of the occlusalsurface.

Control proceeds to block 404, where the hundreds or thousands of imageframes are used to generate an occlusal backbone which is a threedimensional surface representation of the occlusal surface.

From block 404, control may proceed either to block 406 or block 408,where either block 406 may be performed before block 408, or block 408may be performed before block 406.

At block 406, a plurality of labial scan segments are generated bymoving the wand 108 in a hook shaped pattern (or some other exemplarypattern) to periodically image a portion of the occlusal surface whileimaging the labial surface. For example, the wand 108 is moved to imagethe occlusal surface of a first tooth (e.g., the last, i.e., third molarat the end of a dental arch), and moved down the side surface of thefirst tooth towards the labial side and then along the side surface ofthe first tooth, second tooth, and third tooth to image a portion of thelabial surface. Then the wand 108 is moved up the side surface of thethird tooth and part of the occlusal surface of the third tooth isimaged to complete the scanning of a first segment of a labial surface.After that the wand 108 is gripped differently and after scanning partof the occlusal surface of the third tooth the wand 108 is moved down tothe side surface of the third tooth, and the wand 108 continues to imagethe side surface of the third tooth, a fourth tooth, a fifth tooth alongthe labial surface before being moved up to scan the occlusal surface ofthe fifth tooth to complete the scanning of a second segment of thelabial surface. Therefore, via a hook shaped or other movement pattern,at least a segment (e.g., spanning 2-6 teeth or more) of a labial scanis obtained. In alternative embodiments, other exemplary patternsbesides a hook shaped pattern may be used for the movement of the wand108. Since the wand 108 may have to be regripped (i.e., gripped indifferent ways) while capturing images of the labial and lingualsurfaces, the scanned images of the lingual and labial surfaces may becaptured in multiple segments. Each segment corresponds to imagescaptured in a single uninterrupted movement of the wand. From block 406,control proceeds to block 410 where the labial scan segments areattached to the occlusal backbone.

At block 408, a plurality of lingual scan segments are generated bymoving the wand 108 in a hook shaped pattern (or other exemplarypattern) to periodically image a portion of the occlusal surface. Theplurality of lingual scan segments are attached to the occlusal backbone(at block 412).

After the labial scan segments and the lingual scan segments have allbeen attached to the occlusal backbone (at blocks 410, 412) then controlproceeds to block 414 where the three-dimensional reconstruction of thedental arch is displayed on the display unit 106.

Therefore FIG. 4 illustrates a flowchart that shows how labial andlingual segments are attached to an occlusal backbone to display athree-dimensional surface reconstruction of a dental arch.

FIG. 5 illustrates a diagram 500 that shows interferometric fringes 502projected by a projector 105 on a dental arch, in accordance withcertain embodiments. In certain embodiments, the intra-oral imagingsystem 102 is a precision opto-mechanical device, based on accordionfringe interferometer (AFI) techniques that measure three dimensionalpoints on an object surface. The AFI technology projects (via theprojector 105) two coherent beams of light, which create a precisioninterference fringe pattern visible on an object surface. In a simplesingle channel AFI system, a series of three two dimensional fringeimages are acquired by an off-axis camera, with the fringe pattern at0°, +120°, and −120°. For each camera pixel, the relative intensities ofthe three measurements may be mathematically combined to calculate aunique distance to the object surface, with the measurement limited bythe width of one fringe. A multi-channel AFI system is not limited to ameasurement width of one fringe, and is, therefore, capable of rapidlymeasuring the topology of intra-oral features.

In FIG. 5, the wand is moved along the line 504 shown superimposed onthe dental arch on which the interferometric fringes are projected. Itmay be observed that the movement of the wand is predominantly along thedirection in which the interferometric fringes are projected. As aresult, the error in surface reconstruction of the occlusal surface isreduced, in comparison to situations where interferometric fringes arenot aligned with the predominant direction of the translational motionof the wand 108.

Therefore, FIG. 5 illustrates certain embodiments in whichinterferometric fringes are projected on the occlusal surface primarilyalong a direction in which the contiguous scan of the occlusal surfaceis performed, to reduce the amount of error in generatingthree-dimensional occlusal surfaces. FIG. 5 illustrates certainembodiments of an imaging system 102, comprising a projector 105 thatprojects interferometric fringes on an occlusal surface of at least apart of one arch of a dentition primarily along an anterior-posteriordirection, and an imaging sensor 112 that is used to view theinterferometric fringes. In certain embodiments, the imaging system 102is configured to generate a contiguous scan of an occlusal surface, andassociate at least one additional surface to the contiguous scan of theocclusal surface. In certain embodiments, the at least one additionalsurface comprises a plurality of labial surfaces and a plurality oflingual surfaces.

FIG. 6 illustrates an exemplary sequence 600 of occlusal frames, inaccordance with certain embodiments. The occlusal frames F1, F2, F3, F4,F5, F6, F7, F8, F9, F10, F11 (shown via reference numeral 602) areacquired successively while traversing the occlusal surface of thedental arch, and each occlusal frame encompasses part of a tooth, asingle tooth, or a plurality of teeth. There is overlap of the occlusalsurface between two successive frames. For example, both frame F1 andframe F2 may image a section of the same tooth.

In certain embodiments, to minimize the effects of noise and certainother image characteristics, frames which overlap by about 50% areselected to construct the occlusal backbone. In other embodiments,frames with a different percentage of overlap may be selected toconstruct the occlusal backbone. In situations where the noise israndom, an overlap of about 50% between two flumes may provide adequatetranslational movement and not too much rotational movement to tit thetwo frames to each other via a process of statistical noise elimination.In other embodiments frames may be selected based on an overlap that mayvary between 15% to 85%. In other embodiments, the optimal percentage ofoverlap may be determined based on analysis of data included orassociated with the frames. In certain embodiments, the optimalpercentage for the overlap may depend of the noise characteristics.

For example, FIG. 6 shows that frames F1, F4, F7, and F10 are selectedto be stitched together (i.e., to be fitted during surfacereconstruction) in a first phase of the construction of the occlusalbackbone. Frames F4 and F1 have an overlapping region of about 50%,frames F7 and F4 have an overlapping region of about 50%, and frames F7and F10 have an overlapping region of about 50%.

FIG. 7 illustrates a diagram 700 that shows how selected frames witharound 50% overlap are used to construct the occlusal backbone, inaccordance with certain embodiments.

In FIG. 7 that is based on the frames F1 . . . F11 shown via, referencenumeral 602 in FIG. 6, Frames F4 and F1 have an overlapping region ofabout 50%, frames F7 and F4 have an overlapping region of about 50%, andthese frames F1, F4, F7 are stitched together in a first phase (shownvia reference numeral 702) to generate a rough occlusal backbone. Thenin a second phase frames F2, F3, F5, F6 are attached (shown via,reference numeral 704) to the rough occlusal backbone to generate a moreaccurate occlusal backbone.

FIG. 8 illustrates a diagram 800 that shows how frames are matched toconstruct the occlusal backbone, in accordance with certain embodiments.Frame P 802 has an associated feature list 803 and a point cloud 804 ofabout 7500 points, and frame Q 806 has an associated feature list 808and a point cloud 810 of about 75000 points. Matching frame P 802 toframe Q 806 in three dimensions, by using the roughly 75000 point cloudpairs is very time consuming. To display the three-dimensional surfacereconstruction in real-time while scanning is being performed, thefeature lists 803 and 808 are used to match frame P 802 to frame Q 806and perform a coarse matching (block 812). The feature lists 802, 808are relatively faster to match. Once a coarse matching is obtained, thena point cloud alignment may be performed with the point clouds 804, 810or other mechanisms may be used to refine the match as shown viareference numeral 813, to perform (at block 814) the three-dimensionalreconstruction.

Therefore, FIGS. 6, 7, and 8 illustrate certain embodiments in which anocclusal backbone is constructed by first using frames that overlap byabout 50% (or on some other percentage based on noise or othercharacteristics), and then other frames are attached to the occlusalbackbone. During construction of the optical backbone frames are firstmatched via matching feature lists to secure coarse fits, before usingpoint clouds to refine the fitting of frames for three-dimensionalsurface reconstruction.

FIG. 9 illustrates a diagram 900 that shows a representation of anocclusal scan 902 with tongue 904, lips 906, and cheek 908, inaccordance with certain embodiments. The tongue, lips, and cheek mayhide portions of the occlusal surface of the dental arch when theocclusal scan of the dental arch is being acquired. The frames of theocclusal scan shows images of the teeth overlapped with portions of thetongue, lips, and cheek, and potentially other elements. The portionsthat represent the tongue, cheek, and lips are removed from the occlusalbackbone.

FIG. 10 illustrates a diagram 100 that shows how tongue, lips, and cheekare removed from the occlusal backbone, in accordance with certainembodiments. In FIG. 10 an exemplary tooth 1002 and cheek 1004 areshown. It can be observed that the surface normals 1006 of the tooth1002 are oriented significantly differently than the surface normals1008 of the cheek 1004. Additionally, if color images are taken theremay be color differences between the tooth and cheek. Since cheek isnon-rigid and tooth is rigid, image characteristics in a sequence offrames may be used to determine non-rigid objects like cheek (or lips ortongue). Therefore, by determining one or more of surface normaldifferences 1010, color differences 1012, rigidity property differences1014, and other cues 1016 the areas of the occlusal scan that representcheek, tongue, and lips are removed from the occlusal backbone.

FIG. 11 illustrates a diagram 1100 that shows the movement of a wand 108in an exemplary pattern, such as in a hook shaped pattern, for labial orlingual scans, in accordance with certain embodiments. Otherpredetermined movement patterns besides a hook shaped pattern may beused in alternative embodiments.

In FIG. 11, the wand may be placed on the occlusal surface of a firsttooth (e.g., the third molar at the end of a dental arch), and moveddown (reference numeral 1102) the side surface of the first toothtowards the labial side and then along (reference numeral 1104) the sidesurface of the first tooth, a second tooth, and a third tooth to image aportion of the labial surface. Then the wand is moved up (referencenumeral 1106) the side surface of the third tooth and part of theocclusal surface of the third tooth is imaged. Therefore referencenumerals 1102, 1104, 1106 show a first segment being acquired for alabial scan.

Subsequent to the first segment being acquired for a labial scan, thewand may have to be gripped once again, and after scanning part of theocclusal surface of the third tooth, the wand is moved down (referencenumeral 1108) to the side surface of the third tooth and the wandcontinues to image the side surface of the third tooth, a fourth tooth,a fifth tooth along (reference numeral 1110) the labial surface beforebeing moved up (reference numeral 1112) to scan the occlusal surface ofthe fifth tooth. Therefore reference numerals 1108, 1110, 1112 show asecond segment being acquired for a labial scan.

Therefore, via a hook shaped movement pattern at least a segment (e.g.,spanning 2-6 teeth or more) of a labial scan is obtained. Multiplesegments of labial scan and multiple segments of lingual scan aregenerated to image the dental arch.

Therefore, FIG. 11 shows certain embodiment, in which by moving the wand108 in a hook shaped pattern or in accordance with other predeterminedpatterns, a plurality of segments of the labial and lingual surfaces areobtained, where each segment also includes portions of the occlusalsurface that may be used to map the lingual and labial segments to theocclusal backbone. In certain embodiments, both the labial and lingualsurfaces have three or four segments each. In other embodiments, thelabial and lingual surfaces may be captured in a different number ofsegments.

FIG. 12 illustrates a first phase 1200 of an exemplary surfacereconstruction of a plurality of teeth by stitching first and secondsegments of a labial surface to an occlusal backbone, in accordance withcertain embodiments. An occlusal surface of the mandibular arch 1202represented via the occlusal backbone is shown and the first segment1204 of the labial surface is stitched (i.e., mapped and fitted) to theocclusal backbone. Then the second segment of the labial surface 1206 isfitted to the occlusal backbone and the first segment.

FIG. 13 illustrates a second phase 1300 of an exemplary surfacereconstruction of a plurality of teeth by stitching a third segment alabial surface and a first segment of a lingual surface to an occlusalbackbone, in accordance with certain embodiments. An occlusal surface ofthe mandibular arch represented via the occlusal backbone 1202 is shownand the third segment of the labial surface 1302 is stitched (i.e.,mapped and fitted) to the occlusal backbone and the second segment ofthe labial surface. Thus the labial surface is completely fitted to theocclusal surface. Then the first segment of the lingual surface 1304 isfitted to the occlusal backbone.

FIG. 14 illustrates a third phase 1400 of an exemplary surfacereconstruction of a plurality of teeth by stitching second and thirdsegments of a lingual surface to an occlusal backbone, in accordancewith certain embodiments. An occlusal surface of the mandibular archrepresented via the occlusal backbone 1202 is shown and a second segmentof the lingual surface 1402 is stitched (i.e., mapped and fitted) to theocclusal backbone and the first segment of the lingual surface. Then thethird segment of the lingual surface 1404 is fitted to the occlusalbackbone and the second segment of the lingual surface. As a result allsegments of the lingual and labial surfaces are fitted to the occlusalbackbone and the three dimensional surface reconstruction of the dentalarch is completed.

FIG. 15 illustrates a flowchart 1500 that shows how an accurate occlusalbackbone is generated by selecting frames that overlap by a determinedamount (e.g., 50% overlap) and by removing areas that represent thetongue, cheek, and lips, and how labial and lingual scans are attachedto the occlusal backbone to display a three-dimensional reconstructionof the dental arch, in accordance with certain embodiments. Theoperations shown in FIG. 15 may be performed via the scanning andsurface reconstruction application 110 that executes operations on theprocessor 104 of the intraoral imaging system 102. In certainalternative embodiments, the operations shown in FIG. 15 may beperformed in one or more computational devices that are external to theintra-oral imaging system 102.

Control starts at block 1502 in which the intraoral imaging system 102scans a sequence of frames in an occlusal scan of the dental arch.Frames with an overlap (e.g., 50% overlap) that are determined based onanalysis of data are stitched, i.e., fitted, (at block 1504) to generatea first phase occlusal backbone. The intra-oral imaging system 102 fills(at block 1506) the other frames (e.g., the frames that did not havearound 50% overlap) to the first phase occlusal backbone to generate asecond phase occlusal backbone.

The intra-oral imaging system 102 removes (at block 1508) the tongue,cheek, lips and other extraneous data from the second phase occlusalbackbone. Control proceeds to block 1510 in which the frames with anoverlap (e.g., 50% overlap) based on the analysis of date are stitchedonce again to generate a third phase occlusal backbone. This restitchingis relatively fast as it can start with positions and orientationsdetermined in the second phase occlusal backbone which are fairlyaccurate, and the new positions and orientations are a minor deviationfrom the previous positions and orientations. The other frames arefilled in the third phase occlusal backbone to generate a fourth phaseocclusal backbone. It should be noted that the fourth phase occlusalbackbone is more accurate in position and orientation and does not havetongue, cheek, or lip data.

The wand 108 of the intra-oral imaging system is used to scan (at blocks1514 and 1516) labial and lingual segments in a hook shaped or someother pattern that periodically overlaps the occlusal surface. Fromblocks 1514 and 1516 control proceeds to block 1518 in which theintra-oral imaging system 102 stitches lingual and labial segments tothe fourth phase occlusal backbone and displays (at block 1520) thethree-dimensional surface of dental arch on the display unit 106.

FIG. 16 illustrates a flowchart 1600 that shows how labial and lingualscans are attached to an occlusal backbone to display athree-dimensional reconstruction of the dental arch, in accordance withcertain embodiments. The operations shown in FIG. 16 may be performedvia the scanning and surface reconstruction application 110 thatexecutes operations on the processor 104 of the intra-oral imagingsystem 102. In certain alternative embodiments, the operations shown inFIG. 16 may be performed in one or more computational devices that areexternal to the intra-oral imaging system 102.

Control starts at block 1602 in which the wand 108 is used to image anocclusal surface of a plurality of teeth of the dental arch of thepatient. A plurality of labial surfaces and a plurality of lingualsurfaces of the plurality of teeth of the dental arch of the patient arealso imaged (at block 1604).

The scanning and surface reconstruction application 110 stitches (atblock 1606) the plurality of imaged labial and images lingual surfacesto the imaged occlusal surface. A digital surface representation of theplurality of teeth based on the stitching of the plurality of imagedlabial surfaces and the plurality of imaged lingual surfaces to theimaged occlusal surface is generated (at block 1608).

FIG. 17 illustrates a flowchart 1700 that shows how labial and lingualscans obtained by moving a wand 108 in a hook shaped or some otherpattern are associated with an occlusal backbone to display athree-dimensional reconstruction of the dental arch, in accordance withcertain embodiments. The operations shown in FIG. 17 may be performedvia the scanning and surface reconstruction application 110 thatexecutes operations on the processor 104 of the intra-oral imagingsystem 102. In certain alternative embodiments, the operations shown inFIG. 17 may be performed in one or more computational devices that areexternal to the intra-oral imaging system 102.

Control starts at block 1702 in which a contiguous scan of an occlusalsurface of one arch of a dentition is generated, where dentition refersto the arrangement of teeth n the oral cavity of a patient. Labial andlingual surfaces are scanned (at block 1704) in multiple segments bymoving the wand 108 in a hook shaped or some other pattern to includeareas of the occlusal surface.

Control proceeds to block 1706 in which the scanning and surfacereconstruction application 110 associates a plurality of labial surfacesof the one arch and a plurality of lingual surfaces of the one arch, tothe contiguous scan of the occlusal surface. The contiguous scan of theocclusal surface is therefore used to generate a three-dimensionalrepresentation of the dentition.

FIG. 18 illustrates a flowchart 1800 that shows how at least oneadditional surface is associated with a contiguous scan of an occlusalsurface, in accordance with certain embodiments. The operations shown inFIG. 18 may be performed via the scanning and surface reconstructionapplication 110 that executes operations on the processor 104 of theintra-oral imaging system 102. In certain alternative embodiments, theoperations shown in FIG. 18 may be performed in one or morecomputational devices that are external to the intra-oral imaging system102.

Control starts at block 1802 in which a contiguous scan of an occlusalsurface of at least a part of one arch of the dentition is generated.Control proceeds to block 1804 in which at least one additional surfaceis associated with the contiguous scan of the occlusal surface.

FIG. 19 illustrates a flowchart 1900 that shows how a plurality oflabial and lingual surfaces are associated with a contiguous scan of anocclusal surface, in accordance with certain embodiments. The operationsshown in FIG. 19 may be performed via the scanning and surfacereconstruction application 110 that executes operations on the processor104 of the intra-oral imaging system 102. In certain alternativeembodiments, the operations shown in FIG. 19 may be performed in one ormore computational devices that are external to the intra-oral imagingsystem 102.

Control starts at block 1902 in which a contiguous scan of an occlusalsurface of at least a part of one arch of the dentition is generated.Control proceeds to block 1904 in which a plurality of labial surfacesand a plurality of lingual surfaces are associated with the contiguousscan of the occlusal surface.

Therefore, FIGS. 1-19 illustrate certain embodiments in which anocclusal backbone of a dental arch is generated from an contiguousocclusal scan, and then segments of labial and lingual surfaces arestitched to the occlusal backbone to generate a three-dimensionalsurface representation of the dental arch. The operations may beperformed in real time via feature matching to generate a coarse matchprior to using point clouds or other mechanisms for matching.Additionally, tongue, cheek, and lip data are removed to secure a moreaccurate occlusal backbone. The generation of the occlusal backboneprior to the labial and lingual scans facilitates the generation of amore accurate three dimensional representation of a dental arch incomparison to the situation in which the occlusal backbone is notgenerated. In certain embodiments, holes may be filled after thethree-dimensional surface of the dental arch has been constructed. Inother embodiments, image compression may be achieved during astatistical noise elimination process achieved by constructing a roughocclusal backbone with only those frames that overlap by around 50% orby some other percentage.

Additional Details of Embodiments

The operations described in the figures may be implemented as a method,apparatus or computer program product using techniques to producesoftware, firmware, hardware, or any combination thereof. Additionally,certain embodiments may take the form of a computer program productembodied in one or more computer readable storage medium(s) havingcomputer readable program code embodied therein.

A computer readable storage medium may include an electronic, magnetic,optical, electromagnetic, or semiconductor system, apparatus, or device,or any suitable combination of the foregoing. The computer readablestorage medium may also comprise an electrical connection having one ormore wires, a portable computer diskette or disk, a hard disk, a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), a portable compact discread-only memory (CD-ROM), an optical storage device, a magnetic storagedevice, etc. A computer readable storage medium may be any tangiblemedium that can contain, or store a program for use by or in connectionwith an instruction execution system, apparatus, or device.

A computer readable signal medium includes a propagated data signal pithcomputer readable program code embodied therein. A computer readablesignal medium may be any computer readable medium that is not a computerreadable storage medium and that can communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device. The computer readable storagemedium is different from the computer readable signal medium.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages.

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, system andcomputer program products according to certain embodiments. At leastcertain operations that may have been illustrated in the figures showcertain events occurring in a certain order. In alternative embodiments,certain operations may be performed in a different order, modified orremoved. Additionally, operations may be added to the above describedlogic and still conform to the described embodiments. Further,operations described herein may occur sequentially or certain operationsmay be processed in parallel. Yet further, operations may be performedby a single processing unit or by distributed processing units. Computerprogram instructions can implement the blocks of the flowchart. Thesecomputer program instructions may be provided to a processor of acomputer for execution.

FIG. 20 illustrates a block diagram that shows certain elements that maybe included in a computational device 2000, where in the computationaldevice 2000 may be the infra-oral imaging system 102, in accordance withcertain embodiments. The system 2000 may include a circuitry 2002 thatmay in certain embodiments include at least a processor 2004. Theprocessor 2004 may comprise any suitable processor known in the art,such as, an arithmetic logical unit, a central processing unit, acircuitry that perform operations, hardware that performs instructionsof a computer program, a microprocessor, a parallel processor, an arrayprocessor, a vector processor, a transistorized central processing unit,a microcontroller, a logic circuitry, etc. Any device that manipulatesdigital information based on one or more operational instructions or ina predefined manner is an example of the processor 2004. The system 2000may also include a memory 2006 (e.g., a volatile memory device), andstorage 2008. The storage 2008 may include a non-volatile memory device(e.g., EEPROM. ROM, PROM. RAM, DRAM, SRAM, flash, firmware, programmablelogic, etc.), magnetic disk drive, optical disk drive, tape drive, etc.The storage 2008 may comprise an internal storage device, an attachedstorage device and/or a network accessible storage device. The system2000 may include a program logic 2010 including code 2012 that may beloaded into the memory 2006 and executed by the processor 2004 orcircuitry 2002. In certain embodiments, the program logic 2010 includingcode 2012 may be stored in the storage 2008. In certain otherembodiments, the program logic 2010 may be implemented in the circuitry2002. Therefore, while FIG. 20 shows the program logic 2010 separatelyfrom the other elements, the program logic 2010 may be implemented inthe memory 2006 and/or the circuitry 2002.

The terms “an embodiment”, “embodiment”, “embodiments”, “theembodiment”, “the embodiments”. “one or more embodiments”, “someembodiments”, and “one embodiment” mean “one or more (but not all)embodiments of the present invention(s)” unless expressly specifiedotherwise.

The terms “including”, “comprising”, “having” and variations thereofmean “including but not limited to”, unless expressly specifiedotherwise.

The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Onthe contrary a variety of optional components are described toillustrate the wide variety of possible embodiments.

When a single device or article is described herein, it will be readilyapparent that more than one device/article (whether or not theycooperate) may be used in place of a single device/article. Similarly,where more than one device or article is described herein (whether ornot they cooperate), it will be readily apparent that a singledevice/article may be used in place of the more than one device orarticle or a different number of devices/articles may be used instead ofthe shown number of devices or programs. The functionality and/or thefeatures of a device may be alternatively embodied by one or more otherdevices which are not explicitly described as having suchfunctionality/features.

The foregoing description of various embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many embodiments of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

What is claimed is:
 1. A system, for generating an intra-oral scan of adentition, the system comprising: a memory; and a processor coupled tothe memory, wherein the processor is configured to: generate acontiguous scan of an occlusal surface of at least a part of one arch ofthe dentition, remove image data of soft tissue from the contiguous scanof the occlusal surface based at least in part on an analysis of 3D datafrom the contiguous scan to distinguish between image data of thedentition and the image data of the soft tissue, wherein the soft tissueincludes at least one selected from a group consisting of a tongue, acheek, and a lip, and associate a scan of at least one additionalsurface to the contiguous scan of the occlusal surface by analyzing thescan data to identify a portion of the scan of the at least oneadditional surface that overlaps with a portion of the contiguous scanof the occlusal surface, wherein the scan of the at least one additionalsurface includes a sequence of image frames including a plurality ofimage frames of the occlusal surface interspersed with a plurality ofimage frames of the at least one additional surface, and determining aposition of the scan of the at least one additional surface relative tothe scan of the occlusal surface based on the identified overlappingportions, wherein the processor is configured to generate the contiguousscan of the occlusal surface by capturing a plurality of partiallyoverlapping image frames of the occlusal surface and stitching theoverlapping image frames together to form a 3D model of the occlusalsurface, wherein the processor is configured to remove the image data ofthe soft tissue from the contiguous scan by removing the image data ofthe soft tissue from the overlapping image frames used to generate theocclusal scan, and wherein the processor is further configured to updatethe contiguous scan of the occlusal surface by restitching theoverlapping image frames together after removing the image data of thesoft tissue to form an updated 3D model of the occlusal surface.
 2. Thesystem of claim 1, wherein the processor is further configured toassociate a plurality of scans of additional surfaces to the contiguousscan of the occlusal surface, wherein the plurality of scans of theadditional surfaces includes a plurality of scans of labial surfaces anda plurality of scans of lingual surfaces.
 3. The system of claim 1,wherein the plurality of image frames of the occlusal surface from thescan of the at least one additional surface each overlap with thecontiguous scan of the occlusal surface, wherein the plurality of imagesframes of the at least on additional surface includes image frames of alabial or lingual surface, and wherein the processor is configured touse the plurality of image frames of the occlusal surface that isincluded in the scan of the at least one additional surface to determinea position of the image frames of the labial or lingual surface relativeto the contiguous scan of the occlusal surface.
 4. The system of claim2, wherein the occlusal surface is imaged prior to the plurality oflabial and lingual surfaces, and wherein the processor is furtherconfigured to display in real-time a three-dimensional representation ofthe dentition as the plurality of labial and lingual surfaces areimaged.
 5. The system of claim 4, wherein the processor is configured todisplay in real-time the three-dimensional representation of thedentition by performing a coarse matching by matching features as theplurality of labial and lingual surfaces are imaged, and wherein theprocessor is further configured to generate a three-dimensionalreconstruction of the dentition based on a point cloud alignment afterthe plurality of labial and lingual surfaces are all imaged.
 6. Thesystem of claim 1, wherein the processor is further configured togenerate an occlusal backbone by matching selected frames of thecontiguous scan of the occlusal surface that have an overlap based on ananalysis of data.
 7. The system of claim 6, wherein the processor isconfigured to detect the overlap based on noise characteristics of thedata.
 8. The system of claim 1, further comprising: a projector thatprojects interferometric fringes on an occlusal surface of at least apart of one arch of the dentition primarily along an anterior-posteriordirection; and an imaging sensor that is used to view theinterferometric fringes, wherein the processor is further configured togenerate the contiguous scan of the occlusal surface based on theinterferometric fringes sensed by the imaging sensor.
 9. The system ofc1aim 1, wherein the processor is configured to remove the image data ofsoft tissue from the contiguous scan of the occlusal surface based atleast in part on the analysis of 3D data from the contiguous scan bydistinguishing between the image data of the dentition and the imagedata of the soft tissue based at least in part on a comparison ofsurface normals of 3D structures in the contiguous scan.
 10. A computerreadable storage medium for generating an intra-oral scan of adentition, wherein code stored in the computer readable storage medium,when executed by a processor, causes a system to: generate a contiguousscan of an occlusal surface of at least a part of one arch of thedentition by capturing a plurality of partially overlapping image framesof the occlusal surface and stitching the overlapping image framestogether to form a 3D model of the occlusal surface; remove image dataof soft tissue from the overlapping image frames used to generate theocclusal scan based at least in part on an analysis of 3D data from thecontiguous scan to distinguish between image data of the dentition andthe image data of the soft tissue, wherein the soft tissue includes atleast one selected from a group consisting of a tongue, a cheek, and alip; update the contiguous scan of the occlusal surface by restitchingthe overlapping image frames together after removing the image data ofthe soft tissue to form an updated 3D model of the occlusal surface; andassociate a scan of at least one additional surface to the contiguousscan of the occlusal surface by analyzing the scan data to identify aportion of the scan of the at least one additional surface that overlapswith a portion of the contiguous scan of the occlusal surface, whereinthe scan data includes a sequence of image frames including a pluralityof image frames of the occlusal surface interspersed with a plurality ofimage frames of the at least one additional surface, and determining aposition of the scan of the at least one additional surface relative tothe scan of the occlusal surface based on the identified overlappingportions.
 11. The computer readable storage medium of claim 10, whereinthe code, when executed by the processor, further causes the system toassociate a plurality of scans of additional surfaces to the contiguousscan of the occlusal surface, wherein the plurality of scans of theadditional surfaces includes a plurality of scans of labial surfaces anda plurality of scans of lingual surfaces.
 12. The computer readablestorage medium of claim 11, wherein the occlusal surface is imaged priorto the plurality of labial and lingual surfaces, and wherein the code,when executed by the processor, causes the system to display inreal-time a three-dimensional representation of the dentition as theplurality of labial and lingual surfaces are imaged.
 13. The computerreadable storage medium of claim 12, wherein the code, when executed bythe processor, causes the system to display in real-time thethree-dimensional representation of the dentition by performing a coarsematching by matching features as the plurality of labial and lingualsurfaces are imaged, and wherein the code, when executed by theprocessor, further causes the system to generate a three-dimensionalreconstruction of the dentition based on a point cloud alignment afterthe plurality of labial and lingual surfaces are all imaged.
 14. Thecomputer readable storage medium of claim 10, wherein the plurality ofimage frames of the occlusal surface from the scan of the at least oneadditional surface each overlap with the contiguous scan of the occlusalsurface, wherein the plurality of image frames of the at least oneadditional surface includes image frames of a labial or lingual surface,and wherein the code, when executed by the processor, causes the systemto use the plurality of image frames of the occlusal surface that isincluded in the scan of the at least one additional surface to determinea position of the image frames of the labial or lingual surface relativeto the contiguous scan of the occlusal surface.
 15. The computerreadable storage medium of claim 10, wherein the code, when executed bythe processor, further causes the system to generate an occlusalbackbone by matching selected frames of the contiguous scan of theocclusal surface that have an overlap based on an analysis of data. 16.The computer readable storage medium of claim 15, wherein the code, whenexecuted by the processor, further causes the system to detect theoverlap based on noise characteristics of the data.
 17. The computerreadable storage medium of claim 15, wherein the occlusal backbone is afirst occlusal backbone, and wherein the code, when executed by theprocessor, further causes the system to generate a second occlusalbackbone that is more accurate than the first occlusal backbone bylinking other frames that are different from the selected frames to thefirst occlusal backbone.
 18. The computer readable storage medium ofclaim 17, wherein the code, when executed by the processor, causes thesystem to remove the image data of the soft tissue from the contiguousscan of the occlusal surface by generating a third occlusal backbone byremoving, from the second occlusal backbone, areas representing the softtissue.
 19. The computer readable storage medium of claim 18, whereinthe code, when executed by the processor, causes the system to removethe image data of the soft tissue based at least in part on the analysisof 3D data from the contiguous scan by removing the image data of thesoft tissue based at least in part on the analysis of the 3D data and atleast one selected from a group consisting of a difference in color anda difference in rigidity properties.
 20. The computer readable storagemedium of claim 10, wherein the code stored in the computer readablestorage medium, when executed by the processor, cause the system toremove the image data of soft tissue from the contiguous scan of theocclusal surface based at least in part on the analysis of 3D data fromthe contiguous scan by distinguishing between the image data of thedentition and the image data of the soft tissue based at least in parton a comparison of surface normals of 3D structures in the contiguousscan.